Throughout the history of the Post Office, there has been a gradual evolution whereby the Post Office encourages mailers to prepare their mail in such a way as to reduce the effort required on the part of the Post Office for processing such mail. As an inducement to the mailer to prepare the mail in such a manner so as to bring about faster mail processing, the Post Office offers mailers a discount for such things as pre-sorted mail, printing of zip codes and pre-printed bar codes. Discounts are given also when the mail is produced in a manner allowing automatic processing with machines such as optical character recognition (OCR) sorters and bar code readers and sorters.
Even with the present reduced postage rates for pre-sorted zip code mail and the like, the Post Office is experiencing difficulties in processing the mail, not only because of the ever increasing volume of mail that is required to be delivered, but also because a significant amount of mail presented to the Post Office does not have the required postage. The mail pieces may not have sufficient postage because the anticipated weight of a mail piece may be greater than expected. In equipment for processing large amounts of mail, it is frequently a practice to determine the weight of the inserts of a mail piece and together with the known weight of the envelope, the total weight of the mail piece is then calculated and postage applied in accordance with that calculated weight. The mail pieces are placed in trays and these trays are delivered to the Post Office. Frequently, errors occur with regard to the calculated weight and these errors cause delays in the Post Office. In the same way, the thicknesses of the mail pieces are estimated based upon the number of inserts and the anticipated thicknesses thereof. If the mail pieces are too thick, they may prove difficult to process in Post Office automatic processing equipment, or may be beyond the requirements of the postal regulations with regard to mail thickness.